Читать книгу The Handy Psychology Answer Book - Lisa J. Cohen - Страница 255

Test norms allow comparison of any individual’s score with those of the general population. In other words, when a test is normed, it is possible to know the percentile rank of any given score, which means the percentage of people who scored below it. In order to establish test norms, the test is administered to a large sample of people. The average (or mean) score and the standard deviation are then calculated. The standard deviation measures how much the individual scores vary from the average score. Are all the scores clustered tightly around the mean or are they all spread out? If you know both the mean and the standard deviation of a test, you can determine the percentile rank of any score. Thus IQ scores reflect a person’s percentile rank according to the tests’ norms.